In the PDP manufacture, for example, an electrode is formed on a substrate at the image display side. Then, a dielectric layer covering the electrode and a magnesium oxide (MgO) film covering the dielectric layer as a protective layer are formed.
The electron-beam evaporation method is a widely used method for forming the protective layer, since it can form a relatively good quality MgO film at high deposition speeds (cf. “2001 FPD Technology Outlook”, Electronic Journal, Oct. 25, 2000, pp 598-600).
With respect to deposition of the MgO film on the PDP substrate, the substrate is held with a substrate holder, and the substrate holder contacts or is connected to a transfer means such as roller, wire, or chain that transfers the substrate to inside the deposition equipment for consecutively depositing a film on more than one substrate.
However, since the film is deposited on the substrate while the substrate is held by the substrate holder, the film is also deposited on the substrate holder at area other than that holding the substrate. The film deposited on the substrate holder in this way thickens with repeated deposition. The thickened film then peels off into the deposition equipment, generating dust. If such dust is present inside the deposition equipment, the dust may become embedded in the film during deposition or mix with the film material, having a detrimental effect on the quality of the film being formed.
One example of a method for solving this problem is shown in FIG. 9. Substrate holder 1 is configured by aligning multiple frames 2, and substrate 3 of the plasma display panel is held with these frames 2 by its periphery. More specifically, if substrate holder 1 has the structure shown in FIG. 9, the only area other than that holding substrate 3 in substrate holder 1 is opening 4, and thus film cannot adhere to area other than that holding the substrate 3. FIG. 9 (a) is a plan view illustrating the schematic structure of substrate holder 1, and FIG. 9 (b) is a sectional view taken along A-A in FIG. 9 (a).
When the MgO film is deposited, the oxygen vacancy of MgO needs to be suppressed to assure the physical properties of the film as a protective layer. Accordingly, oxygen or gas containing oxygen is introduced during deposition.
In this case, the degree of vacuum during deposition is lower than that in general vapor deposition processes. This shortens the mean free path of the evaporated material (deposition material), which allows a proportion of the deposition material to pass through opening 4 of substrate holder 1 and travel to non-deposition face 3b, opposite deposition face 3a of substrate 3 being held, causing a certain quantity of film material to adhere to non-deposition face 3b. This creates areas in which the deposition material is laid down to different degrees, causing visually different states. Accordingly, there is a detrimental effect on the image display.
The present invention solves this problem, and aims to realize a method of manufacturing plasma display panels that can generate quality images by suppressing attachment of the deposition material to the non-deposition face of the substrate during deposition on the plasma display panel substrate.